Process of cracking hydrocarbon oils



April 10, 1934. J. D. SEGUY PROCESS OF CRACKING HYDROCARBON OILS FiledJan. 2, 1930 v glwuentoz Jean fielallre Jeylg Patented Apr. 10, 1934PATENT OFFICE' PROCESS OF CRACKING OILS nYnnooARBoN Jean Delattre Seguy,Chicago, 111., assignor to Universal Oil Products Company, Chicago,Ill., acorporation of Delaware Application January 2, 1930, Serial No.418,043

11 Claims. (Cl. 196-60) This invention relates to improvements inprocess of cracking hydrocarbon oils, and its novel features are moreparticularly directed to certain improvements in so-called vapor phasecracking. This is a continuation in part of my application, Serial No.242,434jflled December 24, 1927.

With the increasing advent of combustion en gines having highcompression ratios, it has been found desirable to use motor fuelscontaining what are commonly known as antiknock compounds. Theseanti-knock compounds are in some instances increased or produced by thefor.- mation of a relatively large percent of unsaturates in thegasoline or motor fuel. The present invention is adapted in its novelfeatures to produce these anti-knock compounds in part, at least,through the cracking of the vapors in what is generally known as vaporphase cracking.

The invention is also adapted as part of a continuous process to producegasoline or gasoline-like bodies, which are relatively low inunsaturates. In addition, the process can be so operated as to more orless quantitatively control the percent of unsaturates. v

In this application, as will hereafter more clearly appear, I havedescribed my basic process, together with various specimens which may becarried out utilizing the broader idea of the invention, but withmodified details depending upon the results desired, or the character ofoil under treatment.

This process is of such a character that the raw charging stock, whethergas oil, fuel oil, crude or reduced crude, or the like, may be firstsubjected to the well known so-called liquid-- vapor phase crackingunder pressure and certain of the lighter products so formed with orwithout first removing gasoline-like material produced, may then besubjected to vapor phase cracking.

At the same time, if desired, the residue produced from the so-calledliquid-vapor phase pressure operation may be flashed and the flashedvapors from the residue also become in whole or in part a highlydesirable and relatively clean charging stock for the vapor phaseoperations.

.The process may be so carried out that the lighter products, as abovedescribed, from the main pressure cracking operation may beindependently treated from the vapors produced by the flashing of theresiduum, or they may be treated together, as a common vapor phasecracking stock.

Another feature of this invention is that the hydrocarbons which aresubjected to the vapor phase cracking, have prior thereto already beenso treated by the liquid-vapor step as to more or less crack them,whereby the subsequent cracking of such hydrocarbons in the vapor phasepart of the process,,may be easier than would be the case were theraw'charging stockinitially subjected to straight vapor phase cracking;

It iswell known in present vapor phase cracking that the fuelconsumption is high and the incondensible gas loss is large. Inaddition, in present types of vapor phase cracking the carbon productionis high. By means'of the present invention the fuelconsumption ismaterially lowered, the gas losses materially reduced, due in part tothe ability to crack in the vapor phase at a lower temperature than hasheretofore been done, and also the carbonproduction is materiallylessened because of the previously prepared charging stock for the vaporphase operations. These advantages are all' obtained without in any waylessening the production of the desirable anti-knock compounds, butquite the contrary such anti-knock compounds are produced in excess ofthat heretofore possible and with much more satisfactory crackingconditions.

It is to be understood that by means of the presout process the oil isso preliminarily treated prior to the vapor phase operation that itis-in prime condition for vapor phase cracking, because it has i alreadybeen initially cracked with the formation of some unsaturates and thevapor phase part of the operation in reality completes the maximumformation of anti-knock, compounds already previously started.

Heretofore vapor phase processes have only been partially successful ongas oil, but by the present invention heavy fuel oils or crude petroleummay be cracked to obtain the maximum amount of gasoline, and certain ofthe constituents thereof converted into a maximum amount of anti-knockcompounds.

Another feature of the invention is thatthe reflux produced from thevapor phase cracking, may, if desired, be re-treated in the liquid-vaporphase part of the process, and inasmuch as this reflux contains initself a large amount of antiknock compounds the gasoline from theliquidunderstood, however, that its broader aspect the invention is notlimited to the vapor phase cracking at substantially atmosphericpressure, as good results may be obtained even though the vapor phasecracking part of the operation is carried out at superatmosphericpressure or at subatmospheric pressure. For example, the liquid-vaporphase part of the process may be at'say 100 lbs. upwards and the vaporphase cracking at pressures of lbs. or lower.

It is to be understood that these figures are merely illustrative and inno sense intended to limit the scope of invention on the degree ofpressure. r

The invention will be more clearly understood from the followingdescription, reference being had to the accompanying drawing.

This drawing shows a diagrammatic illustration of an apparatus and in myopinion a novel form of apparatus suitable for carrying out theinvention. 'It is to be understood that this dia-' grammatic drawing isnot to scale or intended to Referring to the drawing, a cracking coil 1is positioned in a suitable furnace 2. Raw oil is supplied to the coil 1through feed line 3 and feed pump 4, leading to any suitable source ofsupply. The oil passes from coil 1 to transfer line 5, having throttlevalve 6, into expansion chamber '7. The vapors pass out of reactionchamber 7 through vapor line 8 and thence, if desired, into the lowerside of dephlegmator 9. Throttle valve 10 is interposed in line 8 for apurpose hereinafter described.

From the top of the dephlegmator the vapors may pass through vaporoutlet pipe 12, into condenser coil 14, and then to receiver 15.Receiver 15 is provided with gas outlet control valve 16,, and liquiddraw ofi control valve 17.

The temperature of the dephlegmator may be controlled either byintroducing raw oil directly into the vapors in the dephlegmator throughpipe 18, having'control valve 19, or in the event it is inafterdescribed, then the raw oil may be fed through a closed coil 20, whichclosed coil may, if desired, lead the oil in its passage thereto, to thepump 4.

The reflux condensate from the dephlegmator 9 is drawn off through thelower end thereof through pipe 21, and thence may be returned throughlines 21 and 22 and pump 23 to the raw oil feed line 3. A by-pass 24 maybe provided in line 22 around the pump 23, suitable valves v25 beingprovided as shown.

In the line 21, is provided a throttle valve 26.

The reflux may 0also be passed'through line 27 and branch 28 to vaporphase feed line 29, hereinflash chamber 37. A valve 38 is interposed inthe line 36 and a throttle valve 39 is interposed in an extension of theline 35, below the juncture of the line 35 with the line 36, wherebysome of the residuum may be drawn entirely out of the sys- 7, flashchamber 37 and vapor phase coil 47,.

through the proper manipulation of the lines and valves described andprovided for this purpose.

The vapors which are flashed from the flash chamber 37 pass out throughthe upper part thereof through pipe 40, having throttle valve 41 andthence to the line 29. At the lower end of the flash'chamber 37 is aresiduum draw-01f 42 having throttle control valve 43.

In certain cases the flash chamber 37 may be by-passed and the chamber 7used as a combined reaction or expansion and flash chamber. In suchcases all of the vapors from chamber 7 may either pass to thedephlegmator 9, or they may pass directly to line 29 by means of abranch pipe 44, having throttle valve 45.

A throttle valve 46 may be interposed in line 8 as well as valve 47A inline 29, for a purpose hereinafter described. This line 29 leads to thevapor phase cracking coil 47, seated in a suitable furnace 48. Theoutlet end of the coil connects I The temperature in this dephlegmatormay be controlled either by introducing raw oil directlyintodephlegmator 56, by pipe 57, having control valve 58, orif desiredraw oil may be passed through the closed coil 59, and thence if desiredled to the feed pump-4. The raw oil is not introdueed directly intoeither dephlegmator unless it is desired to send it to the pressurecracking coil 1, or unless it is of such a character that it is so cleana charging stock that it can be passed directly to the vapor phasecracking coil 47, without materially increasing carbon formation in thevapor phase coil.

The vapors pass out of dephlegmator 56 through vapor line 60 tocondenser coil 61 and thence to receiver 62, which is provided with gasoutlet control valve 63 and liquid outlet control valve 64. If desiredthe vapors from dephlegmator 9 may also pass into receiver 62, thuseliminating receiver 15. To this end a vapor pipe 65 having controlvalve 66 may lead from the line 12 to the line 60.

The reflux condensate from dephlegmator 56 passes out of the lower endthrough pipe 67, and

thence through pump 68 to line 69. The by-pass 70 may be provided aroundthe pump with the usual valves 71. The reflux from line 60 may be passeddirectly, if desired, to line 29, by means of pipe 72, having throttlevalve 73 and line 28 thereby going to vapor phase coil 47, or if desiredit may pass via lines Hand 83 having valve '84 into line 33 by openingthe valves 84 and 34 and closing the valve 73 in the line 72, therebygoing to flash chamber 37, or the condensate may be passed from the pipe69 into the line 22 by closing the valve 73 and opening the valve '75,thereby going to heating coil 1; or the condensate may be passed toreaction chamber 7, through line 85 having valve 86, valves 75, 73 and84 being closed; or the condensate may be directed, by propermanipulation of the various lines and connections shown and described,simultaneously to two'or more steps of the process as described. Thereflux from either dephlegmator may be drawn out of the system in partor in toto through branch 77 having throttle valve 78, or branch 79,having throttle valve 80. It may be desirable, particularly when theflashed vapors removed 'from chamber 37 contain substantial proportionsof light desirable portions, to subject said flashed vapors todephlegmation before subjecting them to vapor phase cracking, therebysubjecting only the intermediate portions of the products removed fromreaction chamber 7 to jurther vapor phase cracking. To this effect I'provide for a dephlegmator 87 to which flashed vapors from chamber 37may be directed through line 88 having valve 89. Suitable cooling meansare provided in dephlegmator 87 in the usual manner and raw oil or otheroil distillate may be used therein, in direct or indirect contact withsaid vapors. may be removed from dephlegmator 87 through line 90 havingvalve 91, and depending upon their characteristics and the relativepressures maintained in the various parts of the system, collected withthe other light products of the system or passed through line 92, havingvalve 93, condenser 94 and collected separately at 95. p

The condensate formed in dephlegmator 87 may then be directed throughline 96, having pump 97 to line 29 and vapor phase coil 47. Portions ofsaid condensate may be removed from the system through line 98, havingvalve 99, or it may be returned for further treatment to coil 1, chamber7 or flash chamber 37 through lines not shown. It will be understoodthat, should vapors from .chamber 7 be subjected to vapor phase crackingwithout dephlegmation in column 9,and would they be directed to coil 47through line 44, they would be subjected to dephlegmation with theflashed vapors in dephlegmator 87, the reflux condensate from saidmixtureof vapors being then directed to vapor phase cracking as abovedescribed.

Should it be desirable to subject all vapors from chamber 7 to vaporphase cracking, line 100 having valve 101 is' provided to by-passdephlegmator 87 and direct said vapors directly to vapor phase coil 47.

Upon certain .instances dephlegmators 9 and 87 may be combined, and theflashed vapors combined with vapors from chamber 7, the mixture beingeither dephlegmated, the mixed condensate being then treated furtheraccording to any of the alternatives described; or the mixture beingcracked in vapor phase without preliminary dephlegmation. a

To better control the reaction in the vapor phase part or the process,cold or heated oil may be injected into the discharge of the vapor coil47 through line 102 having valve 103, said oil helping to regulate thetemperature after the oil leaves coil 47.

Describing now the manner in which the invention may be operated, onedesirable method of carrying out the invention is to subject the rawcharging stock to a liquid-vapor phase'pressure cracking operation,flash the residuum therefrom and subject the flashed vapors todephlegmation and the condensate therefrom to vapor phasecracking atatmospheric pressure or pressure lower than the main pressure, andtoalso subject the reflux condensate from the dephleg- 'mator 9 in totoor in part to further treatment in chamber 7L In such case, the raw 011,if

The vapors remaining uncondensed fer temperature of say 750 F. to 950 F.more or less and thence-into the expansion chamber 7.

The vapbrs pass out of expansion chamber 7 through line 8 into maindephlegmator 9. Here the heavier portions are condensed while thelighter vapors pass out through line 12, either into receiver 15 orreceiver 62 by suitably regulating the valves shown in the accompanyingdrawing. The reflux condensate may be drawn out through pipe 21 andthence if desired pass through pipe 81 to reaction chamber 7, or it mayin part also pass through pipes 31, 27 and 28 into the line 29, andthence to the vapor phase cracking coil 47. If desired, part of thereflux condensate, instead of passing to pipe 28 may go from pipe 27 viathe pipe 33, to the line 36. The residuum is drawn off the bottom ofchamber 7 continuously and thence may be passed through the pressurereducing valve 38, and be flashed into chamber 37. The vapors from suchflashing operation thence pass through the pipe 29 into the vapor phasecoil 47 or subjected to dephlegmation in 87, the reflux therefrom beingsubjected to vapor phase cracking. A pressure of 100 lbs. upwards may bemaintained in coil 1, chamber 7, dephlegmator 9 and on receiver- 15, bysuitably regulating the valves 16 and 17 on receiver 15 and valves 32and the reducing valve 38. If desired the valves 74 and 34 may be usedas reducing valves depending upon whether the line 28 or 33 are usedinstead of using valves 32.

The material passing through the vapor cracking coil 47, is subjected totemperatures in said coil of say 900 to 1150 more or less.

It is .to be understood that the temperatures here given areillustrative as well as the temperatures in the transfer line 5. Thevapor phase cracking coil may be maintained under substantiallyatmospheric pressure, or if desired, under a pressure somewhat aboveatmospheric, say 20 to 50 lbs. more or less. If desired, the vapor phasecracking coil may be even maintained under a vacuum, by connectingsuitable vacuum pump to the receiver 62. In such case the pump 68 may beused as a double action pump, vacuum on the inlet and pressure on thedischarge side.

The contents of vapor phase coil 47 are then .preferably passed at acontrolled temperature to chamber 51 where any carbon containingportions may be dropped out and be drawn out of the system, while thebalance goes through the line 54 to dephlegmator 56. In thisdephlegmator 56 the heavier portion will be condensed, and may I then bepassed through the lines 67 and 69 directly back to the main heatingcoil 1. In such case the valves 26, 73, 84 and 86 are closed and thereflux condensate from dephlegmator 56 may then readily pass directly tocoil 1. The portion of the oil which is passed through the vaporphasecracking coil is converted into a relatively large percent ofunsaturates, aromatics or other anti-knock compounds, and may then, ifdesired,

be blended with straight run gasoline or with raw charging stock usedmay, as heretofore stated, be either gas oil, heavy fuel oil or crude,and it may be noted that by the present invention I not only crack suchheavier oils but in doing so separate out therefrom highly desirableclean charging stock already partially cracked, which is very suitablefor the vapor phase operation.

At the same time it will be noted that the charging stock which goes tothe vapor phase cracking coil has not only been partially cracked asheretofore stated, but it thus necessitates a minimum amount of.additional fuel for the vaporcracking coil. Furthermore, inasmuch as theportion of the oil which passes through the vapor phase cracking coilhas already been more or less cracked lower temperatures may be used inthe vapor phase coil, thus materially lessening the objectionable highgas losses incident to heretofore known vapor phase cracking processes.It will be further noted that by this process the gasoline produced bythe pressure operation of the proc ess is removed and not subjected tothe vapor phase cracking. In addition, if the reflux condensate from thevapor phase cracking operation-is returned to the main cracking coilthen the gasoline formed by the pressure part of the process will havemixed with it a certain amount of desirable anti-knock compounds.

Another important feature of thismanner of carrying out the invention isthat the rate and extent of cracking in the pressure part of the processmay be regulated entirely independently of the vapor phase part of thecracking, and also of the reverse is true.

While I have stated that by this process the vapor phase cracking can becarried out at a lower temperature than in certain heretofore knownprocesses, it is to be understood that I in no sense limit myself tosuch temperatures relative to prior processes, because it may bedesirable to subject the oil passing through the vapor phase crackingcoil to very high temperatures, and while this, of course, will not tendto lessen the gas losses, nevertheless the process will still have theadvantages of a low fuelconsumption and a highly desirable chargingstock.

What I claim as my invention is:

l. A process for cracking hydrocarbon oils,

consisting in passing the oil through a heating coil to an enlargedconversion zone maintained under pressure at a cracking temperature,passing products of conversion to a zone of lower pressure therebycausing flash distillation, subjecting the flashed vapors to vapor phasecracking, subjecting the vapors from said vapor phase crack- .ing toreflux condensation, and returning said condensate to said enlarged zoneunder pressure.

2. A process for cracking hydrocarbon oils, consisting in passing theoil through a heating coil to an enlarged zone maintained under pressureat a cracking temperature and where vaporization occurs, separatelyremoving vapors and unvaporized products, passing the latter to-a zoneof reduced pressure, thereby causing flash distillation, subjecting theflashed vapors to vapor phase cracking, subjecting the vapors from saidvapor phase cracking to reflux condensation and returningsaid refluxcondensate to said enlarged zone under pressure. I i

3. A process for cracking hydrocarbon oils, consisting in passing theoil" through a heating zone to an enlarged conversion zoneunderpressure, separately removing vapors and unvapbrized oil from saidenlarged zone, passing said unvaporized products to a zone of lowerpressure, thereby causing flash distillation, subjecting the flashedvapors to reflux condensation, subjecting the reflux condensate to vaporphase cracking, dephlegmating the vapor phase cracked vapors, andreturning reflux condensate thus formed to said enlarged zone underpressure.

4. A process for cracking hydrocarbon oils, consisting in passing oilthrough a heating zone to an enlarged conversion zone under pressure,wherein vapors are evolved, separately removing from said conversionzone the evolved vapors, and unvaporized products, passing the latter toa zone of reduced pressure, thereby causing flash distillation,subjecting flashed vapors and vapors evolved in the enlarged conversionzone to vapor phase cracking, dephlegmating vapors from said vapor phasecracking, and returning reflux condensate' thus formed to the saidenlarged zone under pressure.

5. A process for cracking hydrocarbon oils, consisting in passing oilthrough a heating zone to an enlarged conversion zone under pressure,wherein vapors are evolved, separately removing from said conversionzone the evolved vapors, and unvaporized products, passing the latter toa zone of reduced pressure, thereby causing flash distillation,subjecting flashed vapors and vapors evolved in the enlarged conversionzone to reflux condensation, removing the non-condensed vapors,subjecting the reflux condensate so obtained to vapor phase cracking,dephlegmating vapors from said vapor phase cracking, and returningreflux condensate thus formed to said enlarged zone under pressure.

6. A process for cracking hydrocarbon oils, consisting in passing theoil through a heating zone under a superatmospheric pressure, passingthe heated oil to an enlarged zone at conversion temperature, but undera lower superatmospheric pressure, separately removing vapors andunvaporized oil from said enlarged zone, subjecting cracked vapors, andreturning reflux condensate thus formed to said enlarged conversionzone.

7. A process for cracking hydrocarbon oils, consisting in passing theoil through a heating zone under a superatmospheric pressure, passingthe heated oil toan enlarged zone at conversion temperature, but under alower superatmospheric pressure, separately removing vapors andunvaporized oil from said enlarged zone, subjecting said unvaporizedproducts to flash distillation by further reduction in pressure therebyseparating vapors, subjecting said flashed vapors to refluxcondensation, removing uncondensed vapors, subjecting the refluxcondensate to vapor phase cracking, dephlegmating the vapor phasecracked vapors, and returning reflux condensate thus formed to saidenlarged conversion zone.

8. "A process for cracking hydrocarbon oils, consisting in passingthe-oil through a heating coil to an enlarged zone maintained underpressure at a cracking temperature and where vaporization 'occurs-separately removing vapors and unvaporized products,,passing the latterto a zone of reduced pressure, thereby causing flash said enlarged zoneunder pressure, and subjecting vapors from said enlarged zone to vaporphase cracking.

9. A process for cracking hydrocarbon oils, consisting in passing theoil through a heating zone to an enlarged conversion zone underpressure, separately removing vapors and unvaporized oil from saidenlarged zone, passing said unvaporized products to a zone of lowerpressure,

thereby causing flash distillation, subjecting the flashed vapors toreflux condensation, subjecting.

the reflux condensate to vapor phase cracking, dephlegmating the vaporphase cracked vapors, and returning reflux condensate thus formed tosaid enlarged zone under pressure, and subjecting vapors from saidenlarged zone to vapor phase cracking. i

10. A hydrocarbon oil cracking process which comprises passing the oilthrough a heating zone and heating the same therein to crackingtemperature under suflicient pressure to maintain a substantial portionthereof in liquid phase, discharging the heated oil into an enlargedreaction zone maintained at cracking temperature and undersuperatmospheric pressure, removing unvaporized oil from said enlargedzone and flash distilling the same by pressure reduction, passing theresultant flashed vapors and the vapors evolved from the oil in saidenlarged zone, without prior condensation of any substantial portionthereof, to a dephlegmating zone and subjecting the same to commondephlegmation therein to condense heavier fractions of the admixedvapors, subjecting resultant reflux condensate in a second heating zoneto an independent cracking while substantially in the vapor phase, anddephlegmating and condensing the vapor phase cracked vapors.

11. A hydrocarbon oil cracking process which comprises passing the oilthrough a heating zone and heating the same therein to crackingtemperature under suflicient pressure to maintain a substantial portionthereof in liquid phase, discharging the heated oil into an enlargedvap01 separating zone and separating the same therein into vapors andunvaporized oil, separately removing the vapors and unvaporized oil fromthe enlarged zone and flash distilling the latter by lowering thepressure thereon, combining the flashed vapors, without priorcondensationof any substantial portion thereof, with the vapors removedfrom the enlarged zone and dephlegmating the vaporous mixture tocondense heavier fractions thereof, passing resultant reflux condensateto a second heating zone maintained at higher temperature than thefirstmentioned heating zone and cracking the same therein whilesubstantially in vapor phase, and dephlegmating and condensing thecracked vapors from said second heating zone.

' JEAN DELATTRE 'SEGUY.

